Abstract

The acute experimental poisonings described in the literature show that cannabis resin has an overall biologically harmful effect on the organism. Little research has been done on the harmful long-term effects of cannabis resin on the organism.

A. I. DURAND1NA Chair of Psychiatry (A. I. Durandina, Senior Lecturer) of the Kirghiz Government Medical InstituteV. A. ROMASENKO Institute of Psychiatry of the Academy of Medical Sciences of the USSR(Director: Professor A.V. Snejnevski, Active Member of the Academy of Medical Sciences of the USSR)

The acute experimental poisonings described in the literature show that cannabis resin has an overall biologically harmful effect on the organism. Little research has been done on the harmful long-term effects of cannabis resin on the organism.

Chopra R.N. and Chopra C. S. ([1] ) subjected two monkeys to the smoking of hashish for 90 days. For the first three weeks, the animals had an aversion to inhalation. When subjected to smoke containing from 0.5 to 2.0 g of cannabis resin, the animals became restless and tried to close the orifice through which the smoke was entering the chamber. Within three weeks, the animals started to like the smoke and they started to inhale. At the end of the fourth week, the monkeys became sluggish as a result of the influence of the smoke, moved and sat with difficulty, concentrated their gaze on one point and suffered from epiphora. Their gait became unsteady and they were occasionally restless. They looked confused. They suffered from diarrhoea, loss of weight and cachexia and they finally died.

In experiments on dogs, D. H. Kazieva ([2] ) induced chronic cannabis resin poisoning over a period of two months. The animals were given a daily exposure by inhalation. The quantity of cannabis resin smoked varied between 5 and 8 g, depending on the weight of the animal. In the initial stages of exposure, all the functions of the animals were observed to be inhibited. In the author's opinion, this state corresponded to unconsciousness. Subsequently, refusal to eat and catalepsy were observed.

* The original of this article is in Russian.

Miras ([3] ) carried out experimental research on rats which were given cannabis resin over a period of five months. At first the animals suffered from diarrhoea for 30 days, which stunted their growth. In the fourth month, their weight was found to differ considerably from the weight of the control group. Also, the animals became depressed from the second day of exposure.

The author studied the same animals' ability to reproduce. After five months of chronic exposure, animals were mated. The ability to reproduce turned out to be considerably lower than for the control group. Many animals died after giving birth although they had not been receiving cannabis resin during this time.

Our research was conducted on eight healthy adult dogs weighing from 12 to 21 kg. For our experiments, we used preparations of Yujnochuisk cannabis resin not previously studied and we studied some of the functional, neurological, biochemical and morphological changes occurring in chronic cannabis resin poisoning.

We administered the cannabis resin in large doses of from 0.5 to 3.0 g per 1 kg of body weight. The initial dose was based on a calculation of 0.5 to 1.0 g per kg of weight. The dose was then increased in the light of the animals' reaction to cannabis resin and of their condition. The cannabis resin was administered with the animals' food. If the animals did not eat the treated food, they were given a single daily dose per os. Exposure continued until the animals died. Their behaviour - their reactions to the experimenter, to new people, noise, injections and food - was studied before exposure and throughout the experiments. Electrocardiograms were recorded weekly on a Riva-Rocci apparatus and the arterial pressure was measured in the carotid artery. To this end, a month before the beginning of the experiments the right carotid artery was led out into a skin flap by the Van Leersum method.1The rate of the blood circulation was measured. Cytitone in a concentration of 1 ml to 9 ml of distilled water and in a dose of 0.1 ml per kg of weight was rapidly introduced into the lateral subcutaneous vein of the leg. A check was made on the time taken from introduction of the cytitone solution to the manifestation of deep inhalation, on the rhythm and quantity of breathing; the activity of the gastrointestinal tract was observed and temperature was measured. The animals were weighed regularly during the experiments. As was done in the case of acute experimental cannabis resin poisoning, the blood was checked for red cell and white cell counts, haemoglobin count, blood formula, plasma protein level (in percentages) and blood sugar level; the quantity of adrenalin-like substances and the cholinesterase activity were also checked.

The animals were under observation for from 15 to 73 days before the experiments began. All the animals had lively reactions to their environment, they developed a lively orientated reflex, they pricked up their ears at the appearance of new people and in response to tapping, they barked and looked around and sometimes they put their tails between their legs. They had good appetites.

As a result of cannabis resin poisoning, all the animals suffered from light or medium depression which turned into prostration on the last day of their life.

The depression was permanent in some animals and intermittent in others. Against this general picture of depression, most of the animals experienced fits of marked restlessness at different times; upon examination they were found not to be lying down all the time but to be jumping around some of the time and lying down some of the time; they frequently nodded their heads and barked. All the animals were also observed to be timid and frightened. The dogs looked around, put their tails between their legs, hid in corners or hid behind other animals; they trembled a lot in response to unexpected noises and tapping. The fits of restlessness and timidity were of brief duration and were followed by a return to the depressed state. Marked aggressiveness was observed in all the animals at different times, the dogs becoming bad-tempered and snarling. When being examined they tried to bite. They reacted over-sensitively to injections, they whined and barked and pulled away from the table. Prior to the experiments they had been quiet during these events.

The motor system of the animals became disturbed at various times; co-ordination was impaired and there were symptoms of hyperkinesia, fibrillary tremor and muscular rigidity. Of these symptoms the most frequent were co-ordination disturbances of varying degrees of severity. The first degree is defined as a barely perceptible lateral swaying, almost imperceptible when the animal is standing. The second degree, which was more frequently observed, is defined as noticeable lateral swaying and swaying around the longitudinal axis of the body in the standing position. The third degree, which was also fairly frequent, is defined as moderate confusion or falling while walking. The fourth degree - defined as complete loss of ability to stand on the legs and to maintain a steady position - developed in only one case during the first week. In subsequent weeks the impaired co-ordination of this particular dog was of second-degree severity and intermittent.

In all our observations, therefore, there was impairment of co-ordination; however, it was of the nature of cerebellar ataxia and, despite prolonged exposure, the severity of the disturbance decreased in some animals (three) while in some cases the co-ordination disturbances occurred only intermittently.

The fits of hyperkinesia were myoclonic. At times there were noticeable rapid twitchings of some body muscles and of the front and rear extremities (five).

Fibrillary tremor was observed in six animals. Occasionally there was a mild fit-like trembling of the whole body or of individual parts of the body; the part mainly affected was the head, but sometimes the paws were affected too. A few hours before death some animals (four) developed tonic and clonic spasms.

Muscular rigidity and other symptoms of cannabis resin poisoning developed at various times and were observed in half of the cases. The degree of severity varied from moderate to acute muscular tension. In the moderate degree, the animals' muscles were tensed but the animals could make passive movements with their extremities and their whole body. In the acute degree, the muscles were so tense that the animal could not make passive movements. The dogs contracted into ball-like shapes and when endeavours were made to shift them from this position they looked round and howled. Catalepsy was observed in some animals (two).

In the course of our experiments we gave individual exposures to cannabis resin to animals already suffering from chronic cannabis resin poisoning so as to explain special behavioural features and the neurological symptoms of this condition. The experiments were carried out on four dogs.

Single exposures to cannabis resin were made in the sixth week of chronic cannabis resin poisoning when its symptoms had become dearly marked. The daily dose in such cases (7.5 to 48.0 g) was given per os and the animals were observed in the operating theatre for two or three hours. The exposure continued for one to five days. Forty such observations were made.

In the case of a single exposure to cannabis resin of animals already suffering from chronic cannabis resin poisoning, the symptoms of acute cannabis resin poisoning were less marked than for the initial exposures. Most frequently the animals remained just as depressed as before the exposure. Less frequently, a mild state of depression deteriorated at times into the medium state. Sometimes the animals became stimulated, but the stimulation was less marked than the depression and of brief duration. Scleral hyperaemia developed or increased in severity in all the animals. There were some cases of hypersalivation and of dryness of the mouth, and vomiting was occasionally observed.

Co-ordination disturbances too were less severe than for the initial exposure. Other symptoms of disturbances of the motor system (body tremor, muscular rigidity, catalepsy, hyperkinesia) were noted in a few cases. The symptoms of chronic cannabis resin poisoning were " tidal " - i.e., they would appear and then disappear, apparently in connexion with the adaptation of the organism to the drug. This and increased tolerance may explain the less marked developments of acute cannabis resin poisoning in the case of a single exposure of animals already suffering from chronic cannabis resin poisoning. Despite the temporary adaptation of the organism and the organization of the compensatory adaptive functions, they finally became deranged and the animals died.

A comparison of our experiments with similar experiments with Indian cannabis described in the literature shows that the animals' behaviour and the neurological changes in them are identical for both Indian and Yujnochuisk cannabis.

Our observations revealed that, as in the case of Indian cannabis, prolonged poisoning with Yujnochuisk cannabis causes depression in the animals. Similar disturbances were also observed in the nervous system, such as the dilation and contraction of the pupils, a weakening or disappearance of the pupillary reactions to light, disturbed co-ordination, etc.

As in the case of acute cannabis resin poisoning, the pathological process is of the nature of toxic encephalopathy.

In both the chronic and acute cases, the neurological changes in the brain are polymorphic and diffused. In contrast to acute poisoning, degenerative changes in the ganglion cells are the main pathological factors in chronic poisoning.

Haemodynamic disturbances were in the majority of cases moderate or entirely absent, in contrast to acute cannabis resin poisoning.

The main symptoms in the ganglion cells of the cerebral cortex were corrugation of the cells and caryocytolysis, the latter being combined with hydropic degeneration or other symptoms of pathological changes in the cells, (hyperchromatosis, chromatolysis). Acute satellitosis was found in the most diseased parts of the nerve cells. In the majority of cases the degenerative processes in the chronic case terminated in the death of the nerve cells (five animals). This led to relatively marked foci of loss of nerve cell substance (Fig. 1).

FIGURE 1.

"Spot ". Cerebral cortex. Section through the second and third layers, caryocytolysis. Nissl X 100

Haemodynamic disturbances were less frequent in the subcortical nuclei than in the cortex and were distinguished by congestion of the veins and perivascular oedema. There was corrugation of the nerve cells in the subcortical nuclei just as in the cortex, the corrugation being combined with various degenerative symptoms and in a few cases with hydropic degeneration (Fig. 2).

Haemodynamic disorders of the medulla oblongata were found only in a few places, in the form of perivascular oedemas.

The nerve cells of the susceptible nuclei were particularly subject to pathological changes. In nearly all cases a darkening of these nuclei was observed, occasionally accompanied by chromatolysis or in a few cases severe nerve cell disorders (Nissl type) and with disturbances to the cells of a near-ischaemic nature.

FIGURE 2.

In the nerve cells of the motor nuclei, swelling and, in isolated cases, pyknosis of the nuclei and chromatolysis occurred.

Corrugation and disappearance of the purkinje cells were the most characteristic changes in the cerebellum; swelling of the purkinje cells was less common. In a few cases individual symptoms of degeneration (hypochro-matosis, pyknosis of the nuclei, neuronophagia) were found.

There were only a few cases of haemodynamic disturbances. Briefly, the pathomorphological changes occurring in the chronic experimental cannabis resin poisoning of animals include diffused nerve cell disorders in the form of corrugation, caryocytolysis, hydropic degeneration and various symptoms of degenerative changes, darkening hyperchromatosis, chromatolysis, pyknosis of the cell nuclei, etc. Corrugation of the nerve cells in the cerebral cortex, the subcortical nuclei and the cerebellum was the most characteristic form of degeneration in chronic cannabis resin poisoning. According to our data, corrugation of the nerve cells in cannabis resin poisoning is a very acute form of disorder and was observed in acute cannabis resin poisoning in those cases in which the animals died. These facts, and the prevalence of cell corrugation in all cases of chronic cannabis resin poisoning terminating in death, support our opinion about severe damage to the parenchyma of the brain.

Haemodynamic disturbances in chronic cannabis resin poisoning are less severe than in acute cannabis resin poisoning. It may therefore be possible that prolonged exposure to the drug may trigger off a corresponding adaptation to the poisoning. The pathological process in the nerve cells is a protracted one since they are the most susceptible to changes in the external and internal environment. In this connexion there are severe disturbances of the complicated functional relationships in the nervous system and in the organism as a whole.

Chronic poisoning by resinous substances containing Yujnochuisk cannabis caused a change in heart beat, coronary insufficiency and a change in the myocardium. The heart-beat rate of the animals would intermittently slow down and speed up, with a general tendency to slow down. A convincing and statistically reliable slow down occured in the second, third and fifth weeks (90.6 ± 7.30; P 0.05; 81.6 ± 1.26; P 0.01; 79 ± 9.63; P 0.02, as compared with the original rate of 121.7 ± 8.77 beats/minute). The animals showed signs of coronary insufficiency at various times within 1-21 days from the beginning of exposure. Symptoms also developed which indicated disturbances of the myocardiac metabolism. The change in the R-wave is related to this. The amplitude of the R-wave was observed to decrease either gradually by 2-9 mm or periodically by 2-5 mm. The R-wave became saw-toothed in some animals in the final phase of the experiments within 3-14 days of death.

An example of the decrease of R-wave amplitude and of the change in the diphasic T-wave is shown in figure 3.

The arterial pressure altered at times during chronic cannabis resin poisoning; in a few cases it dropped by 14-60 mm mercury column during the first two weeks. It subsequently varied, with a general tendency to decrease. The drop in arterial pressure was very marked during the last few days of the experiments. In other cases the arterial pressure rose in the second and third weeks, then dropped.

The analysis of our data shows that the arterial pressure tended to drop in chronic cannabis resin poisoning and at the first exposure of the animals to cannabis resin.

These clinical developments are indicative of inhibitions of the vegetative centres, particularly of the vasomotor centre and possibly of impaired vascular tone. Also, the disturbance of the heart beat apparently affected the arterial pressure.

The rate of blood circulation definitely slowed down during the first two weeks of the experiment, on the average by 4.0 - 2.6 seconds (19.7 ±1.17; P 0.02; 18.3 ± 0.89; P 0.05 as compared with the original value of 15.7 ± 0.53). During subsequent weeks it varied up and down. In the final stage of the experiments the rate of blood circulation of all the animals slowed down on the average by 2.1 seconds. Examination of the heart under a microscope showed plasma congestion of the vessel walls and oedema of the interstitial tissue. In a few cases moderate hyperaemia and haemorrhages in the endocardium were observed and in the majority of cases there was atrophy and degeneration of the muscle fibre (cloudy swelling, vacuolation).

Judging from the symptoms of disturbed cardiovascular activity, it seems likely that prolonged cannabis resin poisoning causes changes in the central nervous system at the level of the vegetative centres; inhibition of their functional condition leads to a lowering of the blood pressure and to a slowing-down of the rate of blood circulation and of the heart beat. Also, as morphological research showed, cannabis resin has a direct action, damaging the myocardium.

Chronic cannabis resin poisoning was accompanied by a reduction in respiration for the first two weeks.-The average quantity of respiration at this time was 20 - 23.8 as compared with 28.8. Subsequently, and until the end of the 10 weeks, respiration became weaker, on the average by 38.2-55.9 per cent (P 0.05; P 0.01).

A histological examination of the lungs revealed in all cases foci of emphysema alternating with foci of atelectasis. Congested capillaries were frequently observed in the interalveolar septa. In a few cases plasma congestion and sclerosis of the blood vessel walls were observed.

At various times the animals refused food or ate badly, consuming only one-half or one-third of their rations. The refusal lasted in most cases for 24 hours and less commonly for 48 or 72 hours. In nearly all the animals diarrhoea was observed; it was intermittent in most cases and continuous in a few.

The morphological changes in the gastrointestinal tract were distinguished by oedema of the mucous and sub-mucous linings of the stomach. In every case at -least one other pathological symptom was observed too (atrophy or degeneration of the surface layer of the mucous lining, impairment or ulceration of the epithelium of the fossula, necrosis of the mucous lining, swelling of the epithelium of the villi, vascular stasis and plasma congestion of the vessel walls).

In more than half of the cases, oedema of the sub-mucous lining and desquamation of the epithelium were observed in the small intestine. Other pathological symptoms (atrophy or degeneration of the mucous lining, multiple ulceration, oedema of the mucous lining, necrosis of the villi and congestion of the veins of the sub-mucous lining) were observed in a few cases.

Atrophy and ulceration of the mucous lining and oedema of the sub-mucous lining were observed in the larger intestine in half the cases. Other pathological symptoms-swelling and corrugation of the epithelic layer and atrophy of the sub-mucous lining-were observed in a few cases.

Granular and occasional fatty degeneration was observed in the protoplasm of the hepatic cells. Hypertrophy of the Kupffer's cells was noticed in a few cases. Accumulations of brown pigment were found in their protoplasm. The interlobular tissue was found to be sclerotic in some cases.

In the kidneys the capillaries of the glomerules and the vessels of the medullary layer were often infected. The epithelia of the canaliculi were in a state of cloudy swelling and of vacuolar-droplet degeneration. In one case foci of necrosis of the contorted tubules were found. In some cases oedema of Bowman's capsule was observed.

There were clear signs of degeneration in the cortical layer of the adrenal glands; zones of the adrenal gland cortex were indifferentiated in considerable portions. The cells of the glomerular zone were light-coloured. In the downy and reticular zones, the cell boundaries and structure were unclear, with some vacuolation of protoplasm and pyknosis of cell nuclei. In some cases too foci of haemorrhage in the cortical and medullary layers were observed.

A decrease of Langerhans' islands occurred in the pancreas. In some cases too there was degeneration of the epithelia of the acini and congestion of the Langerhans' islands.

In the spleen the follicles had often thinned out and the trabeculae had thickened. There was an appreciable accumulation of haemosiderin in the tissue.

An analysis of our data shows that chronic cannabis resin poisoning causes a variety of morphological changes in the internal organs. There are particularly marked pathological changes in the heart, liver, kidneys and adrenal glands, but the symptoms are less marked in other organs-stomach, intestine, pancreas and spleen. The main pathomorphological developments in the internal organs are degenerative changes, in the form of cloudy swellings, and occasional vacuolation of cell protoplasm in individual organs. Fatty degeneration developed in some animals. A noteworthy feature is the considerable microscopic changes in the heart, where in addition to degenerative processes of the myocardium atrophy of the muscle fibres sometimes occurs. The degenerative process in the organs is accompanied by vascular disorders-congestion and occasional diapedetic haemorrhages, plasma congestion of the vessel walls and oedema of the interstitial tissue. In the gastrointestinal tract the pathological process develops in the sub-mucous lining of the stomach and intestine, causing oedemas. There were few other pathological symptoms.

All animals suffered a weight loss which was first noted in the second week and gradually increased subsequently. There was a severe drop in the weight of all the animals in the last week. These factors, together with what we have said about alterations of blood circulation and respiration, point to a disturbance of the vegetative functions.

The count of formed elements in the blood altered in chronic cannabis resin poisoning. By the second week the red cell count of all the animals had decreased (P 0.01). This tendency was maintained subsequently, although variations were observed in the course of the experiments. In absolute terms the red cell count dropped from its original value of 6.52 ± 0.344 to 5.39 ± 0.27; 3.50 ± 0.18.

The statistical data (except for the fourth and seventh weeks) are reliable (P 0.05; P 0.001). The periodical return of the red cell count to and sometimes above its original level must be considered a development of the compensatory adaptive functions. In a few cases this was caused by dehydration associated with diarrhoea.

Exposure was found to cause a permanent statistically reliable decrease of the haemoglobin content (77.6 ±3.58; 13.1 ±0.6; P 0.05, as compared with the original value of 88.1 ±2.23; 14.7 ±0.37 units, g%). The drop in the red cell count and haemoglobin content show that cannabis resin poisoning inhibits erythropoiesis, causing a gradual development of anaemia. Cannabis resin poisoning caused an increase in the white cell count as early as the first week of the experiments. As a rule, the white cell count remained high subsequently (11.9 ±1.39; P 0.05; 18.8 ± 4.31; P 0.05 as compared with the original value of 8.67 ± 0.37 thousand/mm 3).

Chronic cannabis resin poisoning was accompanied by changes in the blood formula which mainly affected the lymphocyte content. In the first week the lymphocyte count increased on the average by 51.0 per cent (P 0.02) and it remained at this level until the sixth week (33.1 ±3.78; P 0.01; 45.6 ± 6.19; P 0.05 as compared with an original value of 20.9 ± 0.79%).The lymphocyte count subsequently varied up and down irregularly.

The monocyte count rose and fell in some animals at different times, while in others there was a definite downward trend. After the fourth week, the monocyte count of all the animals showed a statistically reliable decrease of, on the average, 55.8 per cent (P 0.01). The downward trend from the original value continued subsequently, although some variations were noted in the course of the experiments.

The quantity of segment-nuclears decreased somewhat as a rule, although at various times there was an occasional increase in some of the animals. Nevertheless, there was a general downward trend from the original values. The statistical data for the first, third, fifth, seventh and ninth weeks were statistically reliable (43.7 ± 8.37; P 0.02; 59.7 ± 3.45; P 0.02 as compared with an original value of 69.5 ± 0.265 %).

The rod-nuclears count also increased in some animals and decreased in others.

The basophil and eosinophil count did not change. Erythrocyte sedimentation rates underwent no significant changes.

Chronic cannabis resin poisoning affected the blood sugar level, which fell and rose at various times (P > 0.5; P 0.2). In the concluding phase of the experiments the blood sugar level fell in almost all cases.

Our research shows that cannabis resin poisoning may be accompanied by either a slight drop of blood sugar level or by a significant drop reaching the level of hypoglycaemia.

Cannabis resin poisoning caused a decrease in the plasma protein level of the blood. The most convincing (statistically reliable) decrease occurred in the concluding phase of the experiments during the eighth and tenth weeks (P 0.05; P 0·02). In most of the animals a decrease of the plasma protein level was observed in the concluding days of their lives (5.0 - 3.7 g % instead of 9.24- 7.20 g%).

The content of adrenalin-like hormones prior to the experiments was found to be within limits of 5.5 to 8.6 mkg. Cannabis resin poisoning caused a "tidal" change in this level-i.e., it rose and fell. There was a probable increase in the adrenalin-like substances in the blood during the first and fourth weeks (P 0.5; P 0.2). At other times the statistical data show changes which are not statistically reliable.

The cholinesterase activity in the animals' blood prior to the experiments was 0.84 -1.55. The results of cannabis resin poisoning were that this figure varied up and down. The statistical data indicate a statistically reliable drop in this figure in the fourth and sixth weeks (0.88 ± 0.47; P 0.05; 0.70 ± 0.1; P 0.02 as compared with the original value of 1.15 ± 0.107).

An analysis of our data shows that poisoning caused by resinous substances prepared from Yujnochuisk cannabis causes multiple somato-vegetative disorders as well as behavioural disturbances. It is responsible for disturbances of the cardiovascular system, respiration and gastrointestinal tract and for anaemia and leucocytosis. It is also responsible for several biochemical changes, such as alterations of blood sugar level, blood plasma protein, adrenalin-like substances and cholinesterase activity.

The behavioural disturbances of the animals, the somato-vegetative disturbances, the biochemical changes and the morphological changes indicate radical changes in nervous regulation. Cannabis resin poisoning causes disturbances of the higher brain centres, cerebral cortex, medulla oblongata, the reticular formation of the brain stem, the hypothalamus, thalamus and cerebellum.

As in the case of acute cannabis resin poisoning, the clinical symptoms and morphological changes in the brain are of an encephalopathic nature with relatively severe damage to the nerve cells, particularly in the form of corrugation.

The damage to the brain causes a change and a distortion of the central vegetative regulation, as a result of which many clinical symptoms develop indicative of disorders of many functional systems and of the metabolism. Cannabis resin poisoning also directly affects the tissues and individual organs.

In prolonged cannabis resin poisoning, even if the dosage is increased slowly, the compensatory adaptive functions may become deranged and the animal may die.